Test 3 Crunch Flashcards by Bree Reppy

what emits e-‘s when illuminated?

photocathode

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dynode gain is a ratio of what to what?

2ndary e-‘s to incident e-‘s

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quantity that reflects the dose & volume of tissue irradiated

dose area product (DAP)

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what rad field survey equipment is used in nuclear med?

Geiger-Muller counter

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rad field survey equipment that produces small flashes of light when exposed to rad which is detected by a photomultiplier tube & converted to electrical signals which are then measured

scintillation counter

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increasing the multi-slice value will _______ pt dose

reduce

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DL for uncontrolled area?

2 mrem/wk

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Wt for bone marrow, colon, lungs, stomach?

0.12

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what NCRP report addresses the risk v benefit of limitation of exposure to ionizing radiation?

NCRP report #116

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2 things to consider w secondary protective barriers?

leakage & scatter

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what rad field survey equipment has a wide-range, is accurate and sensitive?

Optically Stimulated Luminescence Dosimetry

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thickness for primary protective barrier?

2 mm pb/Eq

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ionization chambers are used to survey rad levels that exceed?

1 mR/hr

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Wt for liver, breast, thyroid?

0.05

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what crystals are used in a scintillation counter? activated by what?

sodium iodide or cesium iodide crystals (Thallium activated)

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Wr for alpha particles?

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expressed in mA/min/wk or mAs/wk

workload (W)

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max acceptable variation in linearity is ___ from one mA station to an adjacent mA station

10%

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peds pt’s require special consideration bc they are vulnerable to?

both genetic & late somatic effects of radiation

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the intensity of scatter radiation 1 m from the pt is about ____ of the intensity of the useful beam

0.1%

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what is good for detecting (not measuring) low rad levels?

Geiger-Muller counter

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intensity of beam @ table-top should not exceed ______ for ea mA station of operation @ 80 kVp

2.1 R/min

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Wr for gamma rays?

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what provides the most recent guidance on radiation protection?

NCRP report #116

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the size of the e- pulse is proportional to what?

the energy absorbed by the crystal from the incident photon

control booth barrier window thickness?

1.5 mm Pb/Eq

height of primary protective barrier?

7 ft

leakage radiation limits at a distance of 1 meter?

leakage rad must not exceed 100 mR/hr

greatest occupational hazard in diagnostic rad?

scatter rad

pt rad dose is expressed as?

entrance skin dose (ESD)

how do you calculate photomultiplier tube gain?

PM tube gain = g^n (g - dynode gain; n - # of dynodes)

where should the primary protective barrier be located in relation to the primary beam?

perpendicular to the beam

thickness for protective eyewear?

0.35 mm pb/Eq

includes glass envelope encasing tube, insulating tube & glass window

inherent filtration

most scintillation counters are?

hygroscopic (swell/crack when absorb water)

what rad field survey equipment is portable and limited to 1 mGy/hr (100 mrad/hr)?

Geiger-Muller counter

rad field survey equipment that is useful in detection of lost rad sources

scintillation counter

aka beam-on T

use factor (U)

emission of light by a thermally stimulated crystal following irradiation

thermoluminescence dosimetry (TLD)

DL for a controlled area?

100 mrem/wk

intensity of high-level fluoro should not exceed what?

20 R/min

Wr for XR?

DL for controlled area?

100 mrem/wk

increasing CT pitch will ______ pt dose

reduce

the means of estimating the genetic impact of low-level radiation on the public

GSD

thickness for protective cover?

0.25 mm pb/Eq

Dg which, if received by every member of the pop., would produce the total genetic effect on the pop as the sum of the individual doses actually received

GSD

added filtration usually amounts to?

1 mm Al/Eq

what NCRP report considers equipment design, performance & use?

NCRP report #102

rad field survey equipment most sensitive to gamma & XR?

scintillation counter

DL for an uncontrolled area?

2 mrem/wk

avg annual gonadal equivalent dose to members of the pop. (of childbearing age)

genetically significant dose (GSD)

thickness for neck/thyroid shields?

0.5 mm pb/Eq

Wt for gonads?

0.2

bucky slot cover should be approx ______ wide at the gonadal level

5 cm

flat contact shield over male reproductive organs decrease's exposure by?

90-95%

what rad field survey equipment is used for photon spectroscopy?

scintillation counter

what is calculated from actual Dg's received by whole pop?

GSD

PBL must be accurate to?

w/in 2% of SID

thickness for Bucky tray cover?

0.25 mm pb/Eq

what significantly reduces the occupational exposure?

use of any device (PBL, filtration, shields) or technique(high kVp, low mAs) that lessens amount of scatter

for stationary fluoro, SSD must not be less than?

38 cm

DL's are based on what kind of dose-response relationship?

L, NT

what are the factors considered when determining thickness requirements for protective barriers?

Use factor (U), Occupancy factor (T), and workload (W) W x U x T

intensity of regular fluoro should not exceed what?

10 R/min

US mean marrow dose?

0.1 rad/yr (1 mGy/yr)

thickness of secondary protective barrier?

1/32" Pb

purpose of filtration?

to increase beam quality, & lessen it's intensity and pt dose to skin & superficial tissue

Wr for protons?

materials of inherent filtration amounts to approximately?

0.5 mm Al/Eq

rad field survey equipment w limited range, very sensitive, & is stationary or portable?

scintillation counter

annual occupational DL is considered a what?

upper boundary

gases used in Geiger-Muller counter?

Helium, Argon, Neon

DAP _______ w increasing field size

increases

what is a nearly tissue equivalent rad dosimeter?

lithium fluoride

what is not good for detecting alpha rad & low levels of rad?

ionization chamber

rad field survey equipment that has a wide-range, is accurate & portable

ionization chamber/cutie pie

total filtration should be at least _______ for a fixed tube at 70+ kVp

2.5 mm Al/Eq

wall thickness of primary barrier? masonry Eq?

1/16" Pb (4" of masonry)

level of radioactivity in the room as a product of max mA & # of XR exams performed per wk

area w occupancy factor more than ___ hrs/wk requires more protection

what is measured using TLDs & calculated using a nomogram, Dg, & bone marrow dose?

ESD

U for secondary barrier = ?

most commonly used type of intensifying screen?

rare earth bc faster & more efficient

for mobile fluoro, SSD must not be less than?

30 cm

NCRP recommends U = ? for walls

1/4

DAP is a better indicator of what?

risk

W of general XR room?

500 mA/min/wk

avg ESD of fluoro?

4 rad/min (40 mGy/min)

basis for gas-filled rad. detectors?

ionization of gas

a gonadal response to radiation can be observed at levels as low as?

10 rads

W of private offices?

\< 100 mA/min/wk

1 TVL = ?

3.3 HVL

Wr for neutrons?

5-20

where should the protective curtain be located?

btw the operator & pt

Wt for skin?

0.01

variation in XR intensity should not exceed

flat contact shield over female reproductive organs decrease's exposure by?

50%

design limits for a controlled area are based on the annual recommended occupational DL of?

5 rem/yr

coll. provides additional _______ of inherent filtration

1 mm Al/Eq

control booth barrier is considered what type of protective barrier?

secondary protective barrier

NCRP recommends U = ? for floors